Ferments Kitchen Basics

Fruit Scrap Vinegar

It’s summer in Florida and I’m in the middle of tropical fruit mayhem. Mangoes just let up, and now my starfruit tree is kicking into gear. Anyone with a starfruit tree knows how prolific those suckers are. A solution for those too-bountiful harvests: Make vinegar. It’s an excellent way to use up ugly or unwanted fruit — the peels, the pits, or bruised, mushy, or otherwise worse-for-wear produce. 

This is a two-stage fermentation process. First ferment alcohol, and then ferment the alcohol into vinegar. Vinegar is the perfect Florida ferment as it loves a hot environment.

Makes: 3 cups


  • Approximately 2 cups fruit scraps of any variety or quality (avoid anything that is actively moldy or dirt-covered. What I do is keep a Tupperware in the fridge and throw all my scraps into it. When I have enough I start a new batch of vinegar)
  • 3 tbsp sweetener of choice (brown or cane sugar, maple syrup, honey) or 5% of water weight, if you're fancy
  • 3 cups water
  • 1 cup unpasteurized vinegar (any apple cider vinegar that’s labeled “with the mother” will work, but eventually you can use previous homemade batches to culture the next one)


  • Roughly chop any whole fruits or very large scraps. Place fruit in a wide mouth mason jar, or another vessel that is taller than it is wide. 
  • In a separate bowl, mix the sweetener into warmish water until it has dissolved, and pour the sugar solution over the fruit scraps. 
  • Weigh down the scraps so they are submerged in the brine. Find a small jar that fits inside of the larger jar is one option. Or press an open ziplock bag into the jar and fill it with water. The goal is to keep the scraps below the liquid and away from oxygen to prevent mold growth on the contents.
  • Cover the jar with a kitchen towel and allow to ferment for 5-7 days at room temperature. Check on the jar every couple days and make sure the scraps remain submerged in the brine.
  • After a week or so, the ferment will be active and bubbling. It will smell and taste like alcohol, and the color of the liquid may darken. Congratulations, you just brewed your own hooch! The sugar in the fruit attracted lactic acid bacteria, which found their way to the jar and went on a binge. They ate all the sugar they could find and converted it into alcohol. Give it a little taste at this point to make sure it worked ; )
  • To transform the alcohol into vinegar, use a fine mesh sieve and strain out the fruit scraps from the hooch. Press to get all the liquid out of the fruit. Pour the hooch in a bowl, or a vessel that is wider than it is tall. The surface of the alcohol should be exposed to as much oxygen as possible. Add the unpasteurized vinegar (the starter culture) to the hooch and whisk it it thoroughly. Incorporate as much oxygen into the ferment as possible. When exposed to oxygen, omnipresent acetobacter bacteria and aerobic yeasts consume the sugars in the alcohol and convert them to acetic acid aka vinegar. 
  • Cover the bowl with a kitchen towel. This will keep bugs and dust out, but allow oxygen access to the ferment. Find a place in the kitchen for the ferment to live, ideally somewhere nice and warm.
  • Stir every day (or every day that you remember) to introduce more oxygen into the ferment. After 7 days begin to taste and smell. When the alcohol has transformed into vinegar it will taste pleasingly sour to you. In my hot kitchen, this generally happens after 7 to 10 days, depending on alcohol content, aeration, and temperature. 
  • After a week, taste the vinegar daily. Once it’s sour, move it to an airtight container for storage as the flavor will start to degrade. Think of it as a bell curve. The longer the vinegar is exposed to oxygen, the longer acetobacter will convert precious acetic acid into water and carbon dioxide, which doesn’t taste good


vinegar mother
Vinegar mother
  • Occasionally during the second fermentation stage (see step 5), a solid mass will form on the surface of the ferment. This is called the mother. Sometimes it’s a solid, gelatinous mat. Sometimes it’s little gooey wispy things. Solid mother formation is not particularly common in my experience, and it’s neither a good or bad sign. The vinegar can still ferment without the formation of a mother. If a mother does form, just strain it out before storing the vinegar away.
  • When it’s really hot out, I occasionally get a white film of kahm yeast (it looks like mold, but it’s not) on top of the vinegar. It’s a harmless yeast, and the worst thing it will do is make the flavor a bit cheesy. Not ideal, but not a deal-breaker. What I tend to do is skip these batches for culinary applications. I just strain out the kahm yeast using a kitchen towel and use the vinegar to make an all-purpose cleaner (see Cleaning Tips from a Dirty Hippie).